1. Field of Invention
This invention pertains to the field of pipe joining. More particularly, the present invention is related to a pipe joint construction wherein two rigid pipe sections are joined in a manner such as to allow for thermal expansion without detriment to the integrity of the joint.
2. Description of the Related Art
In the field of coupling devices, it is well known that there are many ways to accomplish the coupling of two conduits. These methods vary not only for various applications such as low pressure versus high pressure, but also for the materials from which the two conduits are fabricated. For applications of coupling devices for coupling a rigid pipe, such as fabricated from a metal composite, to a flexible pipe, such as plastic or rubber, several different devices have been used heretofore. For example, one construction for connecting rigid pipes to allow thermal expansion incorporates bellows. The bellows expand and contract as the temperature increases and decreases.
Other devices have been provided for joining various types of fluid conduits in an end-to-end fashion. Typical of the art are those devices disclosed in the following U.S. Patents:
U.S. Pat. No.Inventor(s)Issue Date3,211,476J. B. WagnerOct. 12, 19655,190,323H. OetikerMar. 2, 19935,207,460H. OetikerMay 4, 19935,295,718D. D. BartholomewMar. 22, 19945,380,050J. D. Sanders et al.Jan. 10, 19955,775,740K. Fukaya et al.Jul. 7, 19985,794,982H. J. Green et al.Aug. 18, 19986,286,877R. Mendoza et al.Sep. 11, 2001
Of these patents, Wagner ('476) teaches a coupling for use in connecting fluid conduits such as flexible hose, tubing or pipe for handling liquids or gases under pressure or in a vacuum. In this device, a tubular member having a series of radial recesses at one end is received on a threaded tube having an expansion head. The expansion head is aligned with the radial recesses of the tubular member. This assembly is then inserted into a flexible hose, with the expansion head being inserted first. A coupling is then received over the end of the hose, with the threaded tube extending through the coupling. The threaded tube is then engaged to draw the expansion head into the tubular member to expand the radius proximate the radial recesses. The material between the recesses then protrudes into and thereby compresses the hose between the tubular member and the coupling.
Oetiker, in the '323 patent, discloses a high pressure coupling for hoses. The '323 coupling includes a head portion having a “connecting nipple portion” and a “nipple portion” extending in opposite directions from the head portion. A sleeve member made is adapted to be securely connected to the nipple structure by crimping, flanging or the like. The nipple portion includes outwardly projecting, rounded-off ribs cooperating with rounded-off grooves in the sleeve member. The sleeve member is received on a hose and the nipple portion of the coupling is inserted into the hose. The nipple portion is then expanded and the sleeve member compressed such that the hose inserted between the nipple portion and the sleeve member is held securely in position. Oetiker discloses a similar coupler in his '460 patent listed above, as well.
Bartholomew, in the '718 patent, discloses several embodiments of a fitting for positioning on the terminal end of a flexible conduit. The fitting includes a first member positioned on the exterior surface of the terminal end of a conduit, a second member positioned on the interior surface of the terminal end of the conduit, and a connector member coupled with either the first or second member. The first and second members are securely affixed by expanding the diameter of the second member outwardly against the first member to achieve a pressure fit.
Sanders et al., in their '050 patent, disclose a coupling for a tubular hose. The inner peripheral surface of the tubular hose includes an inner corrugated hose made of polymeric material and defines inwardly convex projections extending from one end of the tubular hose to the other end thereof. The coupling includes an insert disposed in the one end of the tubular hose and then radially outwardly expanded into sealing relation with the inner corrugated hose. The insert defines an outer peripheral surface defined by a plurality of outwardly convex projections disposed between the projections of the inner hose, whereby the interior of the tubular hose is substantially sealed to the interior of the coupling.
Fukaya et al., in their '740 patent, disclose a joint structure for joining a small-diameter thin metal tube with a pressure rubber hose. The joint structure of the '740 device is similar to that of Oetiker ('460). Fukaya et al. further disclose a short inner tube inserted into a metal tube in order to define a double wall construction received within the tubular hose.
Green et al. ('982) disclose a method for installing a liner in a metal pipe. A liner is pulled through the pipe, is cut back to the correct position, and a socket clamp or pin clamp is inserted within the liner to hold the liner in place against the interior of the metal pipe. Green et al., teach this method for both male and female portions of a pipe connector such that a continuous liner is formed when male and female portions are engaged.
Finally, Mendoza et al. ('877) disclose a dual seal pipe coupling having cooperating male and female pipe fittings formed on adjacent ends of a pair of conduit members. The male and female pipe fittings define cooperating threads by which they are mated. A pair of seal rings is provided to prevent fluid communication between the pipe fittings under high pressures. At least one of the pair of seal rings is vented at low pressure to prevent pressure build-up and potential seal ring distortion or damage upon initial assembly of the pipe fittings.